The present invention relates to a casing for a laser device, an inside of which laser light passes through, a production method and cleaning method of the same.
A cleaning device for cleaning optical components by radiating laser light is conventionally known, and it is disclosed, for example, in Japanese Patent Application Laid-open No. 2000-82856. FIG. 6 shows the cleaning device disclosed in Japanese Patent Application Laid-open No. 2000-82856, and the prior art will be explained below based on FIG. 6.
In FIG. 6, the cleaning device includes a laser oscillator 101 for oscillating cleaning laser light 102 having a wavelength of an ultraviolet range, a housing chamber 103 for housing an optical component 104, a gas introduction mechanism 105 for supplying a gas into the housing chamber 103, and a gas exhaust mechanism 106 for exhausting the gas inside the housing chamber 103.
On cleaning, the optical component 104 is placed in the hermetically sealed housing chamber 103, and while an oxygen gas is being introduced into the housing chamber 103 from the gas introduction mechanism 105, the oxygen gas is exhausted by the gas exhaust mechanism 106. Subsequently, the cleaning laser light 102 oscillated from the laser oscillator 101 is shaped in beam shaping means 108, and is radiated to the optical component 104 via windows 107 and 107. As a result, ozone and oxygen radicals generate from oxygen, and contaminants such as organic matters and the like adhering to the optical component 104 undergo oxidative decomposition and are discharged, whereby the optical component 104 is cleaned. By performing the cleaning as described above, transmittance of the optical component 104 is increased, and its life is increased.
However, the prior art disclosed in the aforementioned Japanese Patent Application Laid-open No. 2000-82856 has the following disadvantage.
FIG. 7 shows a schematic block diagram of an excimer laser device 109. The excimer laser device 109 includes a laser chamber 112, a front mirror 115, a band-narrowing unit 120 for narrowing a bandwidth of laser light 111, and a monitor module 116 for measuring properties of the laser light 111. The band-narrowing unit 120 includes a band-narrowing box 121, and an optical component 113 is placed therein. The monitor module 116 includes a monitor box 117, and an optical component 114 is placed therein. Further, a light path of the laser light 111 is covered with a cover 119 for preventing the laser light 111 from filtering outside. Hereinafter, the monitor box 117, the cover 119 and the band-narrowing box 121 for covering the light path of the laser light 111 are generally referred to as the casings 117, 119, and 121.
The laser light 111 is irregularly reflected at surfaces of the optical components 113 and 114 or refracted at insides thereof, and strikes inner walls of the casings 117, 119 and 121. In this situation, contaminants such as organic matters and the like also adhere to the inner walls of the casings 117, 119 and 121. Consequently, there arises the disadvantage that the contaminants adhering to the inner walls of the casings 117, 119 and 121 chemically react and are vaporized to adhere to the optical components 113 and 114, thereby contaminating and damaging them.
In addition, the inner walls of the casings 117, 119 and 121 have larger surface area as compared with the optical components 113 and 114, and an amount of adhering contaminants is larger. Accordingly, there arises the necessity to not only clean the optical components 113 and 114 but also remove the contaminants from the inner walls of the casings 117, 119 and 121. Furthermore, optical component holders not shown for moving and fixing the optical components 113 and 114 to set optical axis are placed inside the casings 117, 119 and 121. The optical component holders are complicated in their shapes and have large surface areas, and a lot of contaminants are also adhering to their surfaces. Consequently, the optical component holders also need to be cleaned.
In the prior art, an article to be cleaned is put into the housing chamber 103, and then is radiated with the cleaning laser light 102. However, the casings 117, 119 and 121 are much larger as compared with the optical components 113 and 114, and therefore the huge housing chamber 103 is required to house them. In addition, coatings for keeping fine appearance are applied to or seals and the like for calling attention to how to use are stuck on outer walls of the casings 117, 119 and 121. Accordingly, even if the casings 117, 119 and 121 are put into the housing chamber 103 and are radiated with laser light, a large quantity of organic matters generate from the outer walls, whereby the inner walls and the optical components 113 and 114 inside them are contaminated and damaged.
Further, according to the prior art, oxygen is fed into the housing chamber 103 and the cleaning laser light 102 is radiated. Components used in an F2 laser device need to be cleaned by an F2 molecular laser light oscillated from the F2 laser device or cleaning laser light of a shorter wavelength with higher light quantum energy. This is because even if the casings 117, 119 and 121 are cleaned by cleaning laser light of a longer wavelength, if they are radiated with the F2 molecular laser light with higher light quantum energy again, contaminants generate therefrom.
However, the F2 molecular laser light is absorbed in oxygen very well and attenuated. Therefore, if the F2 molecular laser light is used as the cleaning laser light 102, the cleaning laser light 102 sometimes does not reach the inner walls of the casings 117, 119 and 121 in the atmosphere containing oxygen, and thus the effect of cleaning is reduced. Specifically, in the air or in an oxygen atmosphere, it is difficult to use the F2 molecular laser light as the cleaning laser light 102 and thus it is difficult to apply the prior art to the components of the F2 laser devices.
The present invention is made in view of the above-described disadvantage, and its object is to provide a casing for a laser device, in which contaminants do not generate even if laser light is radiated, a production method and a cleaning method of the same.
In order to attain the above-described object, a casing for a laser device according to the present invention is a casing for a laser device, an inside of which laser light passes through, and has a configuration in that
the inside is previously radiated with cleaning laser light.
According to the above configuration, contaminants adhering to an inner wall of the casing and components therein such as optical component holders and the like can be isolated by radiation of the cleaning laser light. Accordingly, by removing the isolated contaminants, the inside of the casing can be cleaned. Specifically, when the casing is incorporated into the laser device, even if the inside of the casing is radiated with laser light, generation of contaminants is reduced. As a result, it hardly happens that the optical components placed in the inside of the casing are contaminated and damaged, thus reducing the occurrence of power reduction of the laser light and increasing the lives of the optical components.
Further, in the casing for the laser device, the inside may be purged with a predetermined purge gas at a time of the radiation of the cleaning laser light.
According to the above configuration, at the time of the radiation of the cleaning laser light, the purge gas is exhausted, whereby the casing has the isolated contaminants exhausted form the inside. Accordingly, the casing with the inside being clean is provided.
A method of producing a casing for a laser device according to the present invention is
a method of producing a casing for a laser device, an inside of which laser light passes through, and includes
a radiating step of radiating the inside with cleaning laser light; and
a purging step of purging the inside with a predetermined purge gas at a time of the radiation of the cleaning laser light.
According to the above production method, the contaminants adhering to the inside of the casing are isolated by radiation of the cleaning laser light, and on this occasion, the isolated contaminants are discharged from the inside of the casing by exhausting the purge gas. Accordingly, the casing with the inside being clean can be produced.
A method of cleaning a casing for a laser device according to the present invention is
a method of cleaning a casing for a laser device, an inside of which laser light passes through, includes the steps of:
radiating the inside with cleaning laser light; and
at a time of the radiation of the cleaning laser light, purging the inside with a predetermined purge gas to thereby remove contaminants.
According to the above cleaning method, the contaminants isolated by radiation of the cleaning laser light are exhausted to be discharged from the inside of the casing, whereby the inside of the casing can be cleaned. Accordingly, when the casing is incorporated into the laser device, even if the inside of the casing is radiated with laser light, a contaminant hardly generates. Accordingly, it hardly happens that the optical components placed in the inside of the casing are contaminated and damaged. Thus the power reduction of the laser light seldom occurs and the lives of the optical components are increased.
Further, in the method of cleaning the casing for the laser device,
the cleaning laser light comprises ArF cleaning laser light oscillated from an ArF laser light radiating device; and
the purge gas may contain oxygen.
According to the above cleaning method, it becomes possible that the organic matters adhering to the inside of the casing is efficiently made gases to be isolated by oxygen, the ArF cleaning laser light, and ozone generating from the oxygen. Accordingly, the organic matters remaining in the inside of the casing are decreased, thus making it possible to perform cleaning with greater thoroughness.
Further, in the method of cleaning the casing for the laser device,
the cleaning laser light may comprise F2 cleaning laser light oscillated from an F2 molecular laser light radiating device; and
the purge gas may be an inert gas.
According to the above cleaning method, oxygen hardly exists in the inside of the casing, and therefore the F2 cleaning laser light is hardly attenuated. Accordingly, the F2 cleaning laser light is radiated to the inside of the casing with high intensity, whereby cleaning is performed more efficiently. Further, since the F2 cleaning laser light has a short wavelength, the light quantum energy is large, and thus it has a higher efficiency of cleaning off the contaminants. Accordingly, when the casing cleaned with the F2 cleaning laser light is assembled to, for example, the laser device, the contaminants isolated by the laser light are fewer.
Further, in the method of cleaning the casing for the laser device,
radiation of the cleaning laser light, radiation of the ArF cleaning laser light, or radiation of the F2 cleaning laser light may be performed by scattering it to substantially an entire area of the inside.
According to the above cleaning method, it becomes possible to radiate each cleaning laser light to substantially the entire area of the inside of the casing by scattering it, whereby most of the contaminants adhering to substantially the entire area of the inner wall of the casing and the components placed in the inside can be removed.
Furthermore, in the method of cleaning the casing for the laser device,
optical components may be assembled to the inside.
According to the above cleaning method, both of the casing and the optical components are cleaned, and when the casing is assembled to the laser device, it hardly happens that contaminants come out of the casing and the optical components. Further, since cleaning is performed in an assembled state, the chance of a human hand touching the casing and the optical components after cleaning is reduced, and it hardly happens that the cleaned casing, optical components and the like are contaminated and damaged.